Dissociation constants and speciation in aqueous Li2SO4 and K2SO4 from measurements of electrical conductance to 673K and 29MPa

Ion Association in Hydrothermal Sodium Sulfate Solutions Studied by Modulated FT-IR-Raman Spectroscopy and Molecular Dynamics

“…At and above 260 °C the Na 2 SO 4 0 cluster becomes the dominant species, and higher clusters are also present at these conditions, which coincides with our observations from Raman spectroscopy. In addition, the presence of ionic clusters is also in good agreement with the results from Sharygin et al for Li 2 SO 4 solutions, in which neutral clusters up to 24 ions are present at high temperatures.…”

“…In order to assess qualitatively the variation in ion pairing and cluster formation in the simulations, the clusters were arbitrarily categorized into three groups (Table 3) according to the small, medium and large cluster nomenclature described in section 2: 1) small clusters with up to three sulfate ions, whose abundance strongly increases with increasing temperature from 25 to 260 °C and decreases with increasing temperature thereafter (from 260 to 320 °C); 2) medium-sized clusters (Figure 9) containing four or five sulfate ions, the abundance of which is 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 At and above 260 °C the Na 2 SO 4 0 cluster becomes the dominant species and higher clusters are also present at these conditions, which coincides with our observations from Raman spectroscopy. In addition, the presence of ionic clusters is also in good agreement with the results from Sharygin et al 16 for Li 2 SO 4 solutions, in which neutral clusters up to 24 ions are present at high temperatures.…”

“…15 Sharygin et al 16 Hot, compressed aqueous salt solutions have been studied for various water-salt systems, using various spectroscopic techniques. [18][19][20][21][22][23][24][25] Solutions of Na 2 SO 4 and Na 2 CO 3 (which both exhibit type 2 phase behavior, as described above) have been studied using Raman spectroscopy, mostly at room temperature or up to ~200 °C, [26][27][28] but also at higher temperatures and pressures up to >1 GPa using hydrothermal diamond anvil cells.…”

“…The presence of large conglomerates of ions is known from salt solutions in organic solvents which have a low static permittivity . Sharygin et al reported the dissociation constants for the formation of ion pairs in K 2 SO 4 and Li 2 SO 4 solutions at high temperatures from conductance measurements. To fit the data at 400 °C they report that it is necessary to include clusters up to Li 16 (SO 4 ) 8 0 .…”

Critical Review of Transport and Equilibrium Properties of Potassium Chloride in High Temperature Water

“…This is an improvement over similar equations of this form from these same authors. 62,69 3.2. Correlations to Represent Limiting Conductivities: Λ°K Cl , λ°K + , and λ°C l − .…”